Method and system for optimizing a laser system

Abstract

A method for optimizing an optical transmitter is provided. According to one exemplary method, the optical transmitter is optimized by varying three transmitter parameters including the bias voltage, the crossing level and the peak-to-peak voltage. Once the respective optimal levels for the bias voltage, the crossing level and the peak-to-peak voltage are obtained, the optical transmitter is further checked to ensure that the optical transmitter is able to function properly within certain predetermined system parameters. The optical transmitter is also checked under two limiting scenarios to ensure that the optical transmitter is optimized against two predetermined lengths of optical fiber.

1. A method for optimizing an optical transmitter, comprising:
 varying a plurality of transmitter parameters associated with the optical transmitter in sequential order to obtain their respective optimal levels, wherein the plurality of transmitter parameters include a bias voltage, a crossing level and a peak-to-peak voltage, wherein the respective optimal levels of the plurality of transmitter parameters are obtained based on an acceptable level of a performance metric associated with the optical transmitter; 
 varying a bias voltage associated with the optical transmitter to determine its optimal level; 
 with the bias voltage maintained at its optimal level, varying a crossing level associated with the optical transmitter to determine its optimal level; and 
 with the bias voltage and the crossing level maintained at their respective optimal levels, varying a peak-to-peak voltage associated with the optical transmitter to determine its optimal level; 
 wherein the respective optimal levels of the bias voltage, the crossing level and the peak-to-peak voltage are determined based on an acceptable level of a bit-error rate associated with the optical transmitter; 
 and 
 upon obtaining the respective optimal levels for the plurality of transmitter parameters, checking the optical transmitter to ensure that the optical transmitter is able to function properly within a plurality of system parameters. 
 
   
   
     2. The method according to  claim 1  further comprising:
 when varying the plurality of transmitter parameters, maintaining a plurality of optimization constraints within their respective acceptable levels. 
 
   
   
     3. The method according to  claim 2  wherein the plurality of optimization constraints include an extinction ratio, an optical crossing, and an output power. 
   
   
     4. The method according to  claim 1  further comprising:
 operating the optical transmitter at the respective optimal levels of the plurality of transmitter parameters for an extended period of time; and 
 monitoring the performance of the optical transmitter during the extended period of time to ensure that the performance of the optical transmitter remains within an acceptable performance level. 
 
   
   
     5. The method according to  claim 4  further comprising:
 if the performance of the optical transmitter remains within the acceptable performance level for the extended period of time, recording the respective optimal levels of the plurality of transmitter parameters for subsequent use. 
 
   
   
     6. The method according to  claim 4  further comprising:
 if the performance of the optical transmitter does not remain within the acceptable performance level for the extended period of time, repeating the steps of varying the plurality of transmitter parameters and then checking the optical transmitter. 
 
   
   
     7. The method according to  claim 1  wherein the optical transmitter is optimized against an optical fiber having a predetermined length. 
   
   
     8. The method according to  claim 1  wherein the optical transmitter is an integrated laser-modulator and the plurality of transmitter parameters include a laser current. 
   
   
     9. The method according to  claim 1  wherein the plurality of system parameters include an optical signal to noise ratio, a sensitivity level and a dispersion penalty. 
   
   
     10. The method according to  claim 1  wherein the performance metric associated with the optical transmitter is a bit-error rate. 
   
   
     11. The method according to  claim 1  wherein the optical transmitter is an integrated laser-modulator or a non-integrated laser-modulator. 
   
   
     12. The method according to  claim 1  further comprising:
 when varying the bias voltage, the crossing level and the peak-to-peak voltage to determine their respective optimal levels, maintaining one or more optimization constraints within their respective acceptable levels. 
 
   
   
     13. The method according to  claim 12  wherein the one or more optimization constraints include an extinction ratio, an optical crossing, and an output power. 
   
   
     14. The method according to  claim 1 , wherein the optical transmitter is an integrated laser-modulator and the plurality of transmitter parameters include a laser current and wherein varying the plurality of transmitter parameters further comprises:
 varying the laser current to determine its optimal level and maintaining the laser current at its optimal level before varying the bias voltage. 
 
   
   
     15. The method according to  claim 1 , further comprising:
 supplying a test pattern to the optical transmitter; 
 using the optical transmitter to transmit the test pattern to a reference receiver via an optical fiber having a predetermined length; and 
 comparing the test pattern supplied to the optical transmitter to the test pattern received by the reference receiver to determine a bit-error rate associated with the optical transmitter. 
 
   
   
     16. An optical optimization system comprising:
 an optical transmitter configured to transmit a plurality of optical signals, the optical transmitter having associated therewith a plurality of transmitter parameters including a bias voltage, a crossing level, and a peak-to-peak voltage; 
 a reference receiver configured to receive the plurality of optical signals from the optical transmitter; 
 an optical fiber configured to transmit the plurality of optical signals from the optical transmitter to the reference receiver, the optical fiber having a predetermined length; 
 an error detection mechanism configured to determine a bit-error rate associated with the optical transmitter based on the plurality of optical signals received by the reference receiver; and 
 control logic configured to adjust the plurality of transmitter parameters in sequential order so as to achieve a level of the bit-error rate that meets an acceptable performance level; 
 wherein the control logic is configured to perform the following: 
 vary the bias voltage to determine its optimal level; 
 with the bias voltage maintained at its optimal level, vary the crossing level to determine its optimal level; and 
 with the bias voltage and the crossing level maintained at their optimal levels, vary the peak-to-peak voltage to determine its optimal level; 
 wherein the respective optimal levels of the bias voltage, the crossing level and the peak-to-peak voltage collectively result in the level of the bit-error rate meeting the acceptable performance level. 
 
   
   
     17. The system of  claim 16  wherein the control logic is further configured to maintain one or more optimization constraints within their respective acceptable levels when the bias voltage, the crossing level and the peak-to-peak voltage are varied to determine their respective optimal levels. 
   
   
     18. The system of  claim 17  wherein the one or more optimization constraints include an extinction ratio, an optical crossing, and an output power. 
   
   
     19. The system of  claim 16  wherein the control logic is further configured to direct the optical transmitter to operate at the respective optimal levels of the bias voltage, the crossing level and the peak-to-peak voltage for an extended period of time and determine whether the level of the bit-error rate of the optical transmitter remains within the acceptable performance level during the extended period of time; and wherein the control logic is further configured to record the respective optimal levels of the bias voltage, the crossing level and the peak-to-peak voltage for subsequent use, if the level of the bit-error rate of the optical transmitter remains within the acceptable performance level during the extended period of time. 
   
   
     20. The system of  claim 16  wherein the control logic is further configured to determine whether the optical transmitter is able to function properly within one or more system parameters when operating at the respective optimal levels of the bias voltage, the crossing level and the peak-to-peak voltage. 
   
   
     21. The system of  claim 20  wherein the one or more system parameters include an optical signal to noise ratio, a sensitivity level and a dispersion penalty.